In various industries, it can be important to know whether a tank or other vessel contains a substance, a level of the substance in the vessel, and/or an identity of the substance in the vessel. For example, a process (such as, a chemical reaction, a mixing of materials, a supply of material to production equipment, inventorying of materials, etc.) can be significantly affected by an absence of a needed substance, a change in a type of substance present, or a change in an amount of the substance available for the process. Therefore, it will be appreciated that advancements are continually needed in the arts of determining a presence, identity and/or level of a substance in a vessel.